Question

a 25n force is composed of two different components at a right angle to eachother. if one component is 15N, what is the other component?

Answer 1

If two components (say, $F_x = 15N$ and unknown $F_y$ ) are at right angle to eachother, then they satisfiy the Pythagorean's theorem:

$$F^2 = F_x^2 + F_y^2$$

where $F = 25N$ is the magnitude of the force. Expressing the unknown component, obtain:

$$F_y = \sqrt{F^2 - F_x^2}\\ F_y = \sqrt{25^2 - 15^2} = 20N$$

Answer. 20 N.